The field of the present invention relates to terahertz radiation. In particular, terahertz tunable sources, spectrometers, and imaging systems are disclosed herein.
The terahertz (THz) or sub-millimeter-wave region of the electromagnetic spectrum (about 0.1-10 THz) has traditionally represented a relatively under-developed “gap” between the microwave and long-wave infrared regions. Over the last two decades, a new field of spectroscopic sensing and imaging has emerged with the advent of new optoelectronic THz component technology that offers exciting prospects for non-invasive inspection and remote threat detection by combining chemical and biological sensitivity with quasi-optical propagation. Unlike the RF, microwave, and millimeter-wave regions where detection or imaging relies primarily on dielectric contrast, many hazardous materials (e.g. explosives, chemical or biological weapons (CBW) agents, etc.) present characteristic absorption features in the THz frequency range that can be used to detect their presence or to provide enhanced image contrast. Furthermore, unlike optical radiation in the visible and mid-infrared regions, THz radiation is transmitted through a wide range of materials including paper, textiles, wood, plastics, ceramics, etc. Hence, their sub-mm spatial resolution combined with adequate atmospheric transmission provides THz sensors with significant potential for detecting and identifying remote or concealed CBW materials and explosives. A need therefore exists for tunable sources of terahertz radiation, and for spectrometers and imaging systems employing such sources.